Are there any good front end tools to manage a BIND9 server? I'd like to offer users the ability to have a login and manage their hosted zones.
it's simple http://sourceforge.net/projects/smbind/
If you're looking for commercial options, I can suggest Plesk for this - but that may be overkill. It will allow you to set up users and give them a nice interface for managing their Bind zones.
Other than that, I think Webmin allows this feature, as well as some of the other open source hosting control panels.
I use Webmin for my Bind adjustments.
Here is a guide to installing Webmin on Ubuntu 10.10 - Webmin How-to Install Ubuntu 10.10